Any discussion of the ecological damages associated with acid deposition has, as a prominent feature, the effects of habitat acidification on fish and fish populations (Magnuson et aI, 1984). According to Harriman et al (1987), decline in fish stocks due to acidification is thought to have started in Scotland over 50 years ago. Acidic water has probably been the cause of fish mortality in Norway since the turn of the century, although the link to acid deposition was only established in the late 1950s (Henriksen et aI, 1989). Ormerod et al (1990) suggest that trout survival times might have been falling progressively in Wales since the middle of the last century, with the rate of decline apparently increasing significantly in the 1950s (Milner and Varallo, 1990).